In vehicles, the bodywork surface situated between two adjacent glass surfaces is frequently, for stylistic reasons, to be covered by a frequently high-gloss paint film colored black or in a dark color in order thereby to impart the impression at this point of a continuous glass surface. Although generally the two adjacent, vertical frame posts of the window frames in the region of the central pillar of the vehicle are possibilities here, the horizontally situated bodywork strip above the windshield, in the case of vehicles with a lamella roof or glass roof, is also, for stylistic reasons, usually provided with a dark colored paint film in order to provide the visual impression here too of a uniformly continuous surface.
In the case of the lateral application of the paint film, the latter is applied to the frame posts of the window frame of the side doors. Since these bodywork surfaces generally only constitute narrow and short strips, the section of the elongate paint film to be applied is also not particularly large and, in an emergency, could even be applied manually. By contrast, it is a different matter in the case of the horizontally situated bodywork strip in the roof region above the windshield. A paint film section provided for this is not only relatively long and unwieldy and could not possibly be handled by one person on their own; but also access to the application point in the roof region of a vehicle is extremely difficult. In the case of a manual application of a paint film in the front roof region, this could only be carried out by four people who all have to be very well coordinated with one another in order to obtain an approximately crease- and bubble-free application result. Since the paint film remains on the vehicle for the entire duration of use thereof, the paint film has to be correspondingly permanently adhered to the bodywork, with it having to be taken into consideration that the roof portion covered in this manner is situated in the visible region of the vehicle users, at least as they get into the vehicle, and therefore the requirements for a satisfactory application of the film are particularly exacting.
For the automated application method which is mentioned at the beginning and is known from the earlier patent application (DE 102 30 034 A1), a three-layered film composite which is suitable for this is proposed, the film composite bearing a respective surface-covering protective film or a protective paper on both sides of the actual paint film section. For the mechanical handling of the elongate film composite, what is referred to as a contact piece is attached to its two ends, i.e. the protective film strips protrude at the ends. At these contact pieces protruding on the longitudinal side, and only at these, the film composite is grasped from a flat holding-ready position by means of controllable, flat suction grippers of a robotic tool, the suction grippers being tilted outward after picking up the film composite from the picking-up plane. In the case of the known method, the film composite is therefore only grasped at the two narrow sides lying opposite each other and is handled in this manner. The tilting away of the suction grippers enables the film composite, which is held taut and is to be doctored onto the bodywork, is squeezed out of the picking-up plane in a V-shaped manner without the contact surface being partially exposed at the suction grippers. In addition, at one end of the film composite, a second, separate contact piece for the protective film on the adhesive side is provided, which contact piece protrudes over the first contact piece. With the use of this further contact piece, the protective film on the adhesive side can be removed from the film composite in an automated manner before the actual paint film application, i.e. the adhesive side of the paint film can be exposed.
With the technology according to earlier patent application DE 102 30 034 A1 it is indeed possible for the first time, as far as the applicant knows, to apply paint films in an automated manner to bodywork parts, which, in addition to the advantage of release from strenuous and monotonous manual work, has the further substantial advantage of a paint film application which is always in a precise position and is bubble- and crease-free. On the other hand, however, it has been shown in the attempt to use the earlier method and the associated application tool for applying relatively large and/or curved paint film sections to relatively large bodywork portions, i.e. to the roof region above the windshield of a vehicle with a lamella roof or glass roof, that certain problems and/or disadvantages are associated therewith. Firstly, in the case of very large films, an inherent stiffness of the film composite is almost totally ineffective in the sense of avoiding the formation of creases during the application. On the contrary, large paint film sections of the type discussed here would not readily be able to be applied in a crease-free manner using the earlier technology. In addition, curved paint film sections cannot be stretched out from opposite ends in one direction, for example in the longitudinal direction, without creasing. If the robotic tools were constructed according to the model from the earlier application and were dimensioned in accordance with the size of the paint film sections discussed here, they would not only be unjustifiably large and bulky, but also very heavy, which restricts the freedom of movement of the robotic tool. In addition, the robotic tools would be very expensive as a result.